Edible vaccines have received much attention since, in theory, they represent a source of vaccine that would stimulate mucosal immune responses, be cost-effective to produce, be safe to administer, and be stable to ship throughout the world. Studies proposed in this collaborative STTR effort will develop an oral vaccine against a non-toxic form of Staphylococcus enterotoxin B (SEB) by expressing this immunogen in transgenic soybeans. Completion of such studies will be significant since SEB has been identified as a potential agent of bioterrorism, and since no vaccine is presently available. Furthermore, once transgenic soybeans expressing a non-toxic form of enterotoxin B have been produced, these stably transfected plant lines will forever be a renewable source of this edible vaccine. A demonstration of the feasibility and efficacy of expressing an edible human vaccine against a non-toxic, mutant form of SEB in soybeans will be accomplished by performing the following specific aims. Specific aim #1: Expression of an immunogen, mutant SEB, in transgenic soybeans. The purpose of this aim is to characterize expression of a mutant form of SEB in soy milk formulations for use in an oral vaccine. Specific aim #2: To determine the efficacy of soybean-derived SEB as a mucosal immunogen following oral administration. In specific aim #2, we will address whether expression of SEB in transgenic soybean plants can elicit high levels of immunity following oral immunization of mice. Results from these studies will determine the magnitude of the B and T lymphocyte responses following administration of this edible vaccine. In addition, the ability of this edible vaccine formulation to protect against an SEB toxin challenge in a mouse model will be tested. Taken together, these studies will represent a significant, practical advance for the use of edible vaccines that are expressed in transgenic soybeans. In addition, the availability of this renewable resource will provide a product for future Phase II studies. [unreadable] [unreadable] [unreadable]